When you say "contaminated with unburnt powder," are you saying there were actual granules of powder in it? Stuff that looks just like what's in the powder can?

I like 748 and 760 a lot, and shoot those powders a fair amount. What I can tell you is this: If you're loading with one of those two and getting _large_ amounts of soot, or actual unburned granules, then you're almost certainly running them at too low a pressure. Get them into their preferred pressure range (>50k psi, more or less, IME) and they clean up considerably. Even so, I do find them to leave somewhat more soot than some alternatives. That said, an advantage to them is that the carbon/soot is extremely soft and easy to remove, whereas some of the competition appears to burn squeaky clean, but in fact leaves diamond-hard carbon in the barrel that you don't necessarily even see until you bore-scope the gun trying to figure out what in the world has gone wrong with your barrel.

I've heard that Ramshot TAC is quite clean, but I've not used it. I have used Hunter and Magnum, and they're good for cleanliness so far. Nevertheless, I still prefer 748, 760, and Supreme 780.